a tenis ball is dropped from a eight of 20m and bouces to 40% of its previous height with each bounce. what is the total vertical distance the bll has travaelled when it hits the floor for the sixth time.

Answer 1

20 + 2*(sum of 5 terms of GP with a=0.40*20 and r = 0.4)
20 + 2*8*(1-0.4^5)/(1-0.4)
46.3936

or 2*20(1-0.4^6)/(1-0.4) - 20
that is 6 round trips minus the 1st lift